The present invention relates to a device for measuring the speed of the fluid in the annular space of a steam generator, which in particular makes it possible to measure the flow rate close to the walls defining this annular space.
Problems (e.g. corrosion, denting, i.e. constriction of the tubes due to oxidation phenomena in connection with the spacer plates) have occurred in the operation of steam generators of pressurized light water nuclear reactors and are partly due to the thermal and hydraulic conditions prevailing in the vicinity of the exchanger tubes and spacer plates. These conditions are largely dependent on the nature of the flow in the annular space of the steam generator. One of the ways to better understand the aforementioned phenomena is to have information on said flow.
When it is wished to plot the curve of the speed profile in the annular space of the steam generator, the main problem is to very accurately position the measuring points in said space and more particularly very close to the walls, in order to determine the thickness of a possible laminar layer. However, during the putting into operation of steam generators and during transient operating conditions, the instantaneous expansion effects of the inner and outer walls can differ, which makes it impossible to carry out measurements very close to these walls, because this could either destroy the probe, or may not make it possible to know the exact distance between the wall and the measuring point.